Rock drill



Dec. 14, 1937. w. J. MOCZALLUM 2,101,864

ROCK DRILL Filed March 27, 1956 INVENTOR W/LL/AH d. MCALLl/M I y BY ATTORNEY j Patented Dec. 14, 1937 UNITED STATES PATENT "OF-F-lCE I 16 Claims.

This invention relates to an improved, detachable bit for use in drilling into rock and the like. The general nature and purposes of the improved construction are the same as set forth in my pending application Ser. No. 6,942, filed February 18, 1935, for improvements in Rock drill. However, an object of the present improvements has been to simplify the former construction and the mode of producing the detachable bit as well as the mode of applying the same to and detaching it from a drill rod. Another object has been to improve the construction of the bit to strengthen the same and enable it to perform its intended function more efliciently and effectively.

Other objects and advantages of the invention will appear from the detailed description of an illustrative form of the same, which will now be given in conjunction with the accompanying drawing, in which:

Figure 1 is a view looking down upon the cutters of the improved bit at a stage in the production of the bit.

Figure 2 is a side view of the bit at the same stage in its production, portions being broken away and shown in section to better illustrate the construction.

Figure 3 is a view similar to Figure 1 but showing the completed bit.

Figure 4 is a side view of the completed bit applied to the end of a drill rod, portions being broken away and shown in section.

Figure 5 is a transverse sectional view along the line 5-5 of Figure 4, showing the bit from itsinner end.

. Figure 6 is a perspective view of one of the nibs forming part of the bit.

Figure '7 is a face view of a washer element forming part of the-bit, and

Figure 8 is a section through the washer element, along the line 8-8 of Figure 7.

As in my prior construction, the bit comprises a retainer l0 and a plurality of separately formed cutting nibs II. The retainer is preferably formed of a ductile material, such as low carbon steel containing about .15 to .30%' carbon, capable of being readily worked in the required manner and capable of withstanding the strains and shocks incident to rock drilling operations. The nibs I I, on the other hand, are preferably formed of a hard, good quality, cutting alloy, such as a high carbon steel having a carbon content between .5 and 1.5% or any special cutting alloy of suitable character for rock drilling purposes. When these nibs are firmly retained by the member III, in the manner to be explained, there is provided a series of cutting edges capable of resisting to a maximum extent the wear of the stone in the course of drilling, while atthe same time the shocks of'the operation are absorbed to a large degree by the retainer.

The retainer may be formed in any suitable way, as by forging or casting the same, with or without machining to a limited extent or by suitable forming operations upon tubular or other stock of appropriate character. In general, the main body of the retainer is hollow and its lower or socket portion is polygonal in cross section. As shown, it may suitably be provided with four flat sides l2 joined by corner portions l3 having a flat, inner face and a curved outer face. However, both faces of the cornermight be made flat or both curved, if desired, the form of the inner face depending upon the cross section of the drill rod l4, which should be snugly received within the retainer. The upper or nib receivingportion of the retainer may suitably be circular in outer contour and somewhat larger than the socket portion. Four symmetrically arranged, V-shaped projections l5 extend inwardly from the upper portion of the retainer, these projections defining a cross-shaped opening in the upper end. The inner walls of the retainer between the projections |5 or at the ends of the arms of the cross are arranged to slope inwardly toward the axis of the bit at a suitable angle, say about 20 to 30, as indicated at I6. This slope may be continued to the inner surface of the corner I3, at the upperend of the socket portion, or the lower end of the surface It may have its inclination to the axis of the bit increased somewhat or otherwise modified to provide a seat I for a washer element, to be later described. The projections l5 preferably extend only, or not quite, to the plane of the bottoms of the nibs and the seat I60 may extend beneath these projections as well as beneath the nibs.

Each of the nibs in'the improved construction is preferably of the form indicated in Figure 6. The cutting edge I! is formed by a pair of sloping surfaces l8 inclined at a suitable angle to each other, say about Surfaces I9 at the sides of the nib are in planes inclined at a small angle, say about 10, to a. plane bisecting the angle between the surfaces I 8. The width of the nib is such-at its bottom that it may be readily inserted in, and will be snugly received by, one of the arms of the cross-shaped recess in the retainer. Wall 20 at the outer end of the nib is inclined at-an angle corresponding with that of the surface It in the retainer. The opposite end of the nib, however, is preferably formed with a surface 2| arranged to extend sub-- stantially parallel with the axis of the bit. Each of the corners formed between the sides I! and the end 2i is also preferably arranged to extend parallel with the axis of the bit. In view of the slope of the sides l9, this results in the formation of triangular surfaces 22 at the corners specified, disposed at an angle of45 to the end 2!. If desired these corner surfaces may also cut off a portion of the surfaces IS, in which case they will be trapezoidal in form.

In the assembly of the nibs in the retainer they are simply inserted in the arms of the crossshaped recess with their surfaces 20 engaging the inclined surfaces It on the retainer and with the corner surfaces 22 of each nib in engagement with corresponding surfaces on the adjacent nibs. When these parts are so assembled a washer elemm 23, best shownin Figures 7 and 8, is inserted through the openend of the socket portion of the retainer. This washer element is preferably formed of relatively soft, ductile or malleable material which in use will become work-hardened. Malleable iron or steel will be found quite satisfactory for the purpose. In order to permit ready insertion of the washer element, it is preferably cupped or curved, as indicated in Figure 8, so that its outer dimension will be slightlyless than the inside dimension of the socket. It is first inserted with the convex face extending toward the open end of the socket and subsequently a suitable tool is inserted to flatten the element and force its edges into the small cavity I60 formed between the bottoms of the nibs and projections l5 and the edges along which the surfaces i6 intersect the inner walls of the socket. Due to the ductility of the metal of the washer element, it will fiow under the pressure applied into any irregularities in the surrounding surfaces. The formof the cavity I60 may be quite irregular without detriment. The material of the washer will be forced into all vacant spaces, including whatever space may be left between the bottoms of the nibs. In lieu of cupping the washer element, it may simply be formed slightly smaller than the opening in the socket and with slightly added thickness. It may then be caused to fiow into the cavity I60 by reducing its thickness.

It will be understood that when the element 23 is flattened or otherwise forced into the cavity I60, suitable support will be provided at the tops or outer ends of the nibs to retain them in proper relation to the retainer. Either prior or subsequent to or simultaneous with the insertion and fiattening of the washer element, the walls of the retainer will be pressed inwardly at points in line with the projections I5. Any suitable means may be employed to exert the necessary pressure. As the projections are pressed inwardly,-the metal of the retainer will flow and be squeezed against the sloping walls I9 of the nibs and thus firmly lock the nibs in place. They will then be definitely confined against movement in any direction by the combined action of the surfaces I9, 20, and 22 firmly engaging other similar surfaces. If desired the retainer may be heated prior to the squeezing operation to cause the metal to flow more readily and to obtain the benefits of shrinkage of the retainer on cooling.

The washer element 23 is not actually required for the positive and firm attachment of the nibs. Its primary purpose is to prevent loosening of the nibs in the course of hard usage. Should there be any tendency for the nibs to work loose due to excessive strain, this will be prevented or remedied due to the metal of the washer element being forced into any recesses or cavities that may exist at various points, thus automatically tightening the assembly. Accordingly it is not necessary that the washer element be forced into place under any great pressure in the course of assembly of the bit. So long as it is held sufilciently firmly to remain in place its primary function can be accomplished in the ordinary use of the bit. The pounding incident to the first few seconds of its use will not only cause it to fiow into the various recesses around and between the nibs but will gradually bring about work-hardening of the washer element. In a very short time, therefore, there will be provided a relatively hard, tough support for the nibs interlocked with them. At its center the element 23 is provided with a hole 24 aligned with the passage between the nibs to allow for the flow of water, air or the like around the latter.

For the purpose of attaching the bit to the end of the drill rod, one or more pins or rivets 25 are provided. These are preferably provided in the comers ofthe socket, suitable openings 26 being formed to receive the pins. Two such pins are shown-in the drawing at opposite corners of the square, but a greater or less number may be provided if desired. The pins preferably have a sufficiently tight fit in the openings 26 to prevent their accidental removal or loss and to prevent themfrom being accidentally driven into the socket. They areformed of any suitable, soft, rivet metal, such as copper or the like, capable of being readily flattened on the ends in the manner to be explained.

The drill i4 is provided with a notch in one or more corners, this notch providing a shoulder 28 adjacent the pin 25 when the bit is mounted on the rod. This enables the bit to be easily applied to the rod and it is then secured thereto by simply driving the pins into the notches 21. The pins are of sufllcient length to enable a portion to be flattened out or mushroomed at both ends. The

inner end will normally spread sufficiently to substantially engage the shoulder 28 although a slight clearance may be left. In view of the square formation of the drill rod and bit socket and the fact that the work of the bit isaccomplished as the rod is forced against the washer element 23, very little load or strain is applied to the pins 25. These serve simply to retain the bit on the rod in normal handling and in the course of inserting therod and withdrawing it from a hole being drilled.

When the bit has served its usefulness and the nibs are dulled, it is simply necessary to shear the pins 25 at a point adjacent the inner wall of the socket. This may be done by inserting a chisel or the like in the notch 21 and driving it through the pin along the wall of the socket. If the pins are formed of sufficiently soft material, they might be sheared by suddenly withdrawing the bit from the rod in any convenient way. The shearing will then take place between the corner of shoulder 28 and the inner wall of the socket. Any other convenient means may be employed to accomplish the same result. When the pins have been sheared, the bit may be removed by simply.

ened new pins or rivets 25 will be inserted in the holes 26.

While a preferred form of construction has been disclosed in considerable detail and this has certain definite advantages over other forms, it should be understood that various modifications may be made without losing a part, at least, of the benefits and advantages of the construction. The drill rod need not be square in cross-section but may have almost any non-circular form capable of transmitting a torque to the bit when the latter is slid over the end of the rod. The socket portion of the bit should have a configuration substantially similar to that of the rod or should otherwise be capable of being applied to the rod by a sliding movement and caused to turn with the rod when so applied. Other modifications will occur to those familiar with the problems involved.

What I claim is:

1. A rock drill bit comprising a retainer having seats for the reception of separate nibs, a plurality of nibs in said seats, and a washer element within said retainer beneath said nibs, said re-- tainer and washer element being formed of ductile material and having portions pressed into interengagement with said nibs for firmly uniting the parts into a permanent unitary structurel- 2. A rock drill bit comprising a retainer having seats for the reception of separate nibs, a plurality of nibs in said seats, and a washer element within said retainer directly beneath said nibs for supporting the inner faces thereof, said element being formed of a normally ductile material and being forced into interlocking engagement with said retainer and said nibs for permanent connection therewith.

3. A rock drill bit comprising a retainer having seats for the reception of separate nibs, a plurality of nibs in said seats, and a washer element within said retainer directly beneath said nibs and engaging the inner faces thereof, said element being formed of a normally ductile material capable of being readily work-hardened.

4. A rock drill bit comprising a sleeve-like retainer formed of ductile material, a plurality of hard cutting nibs inserted in one end of said retainer and extending therefrom, and a partition of ductile material extending across said retainer beneath said nibs and in engagement therewith, said retainer and partition being pressed into engagement with said nibs to firmly unite the parts into a permanent unitary structure.

5. A rock drill bit comprising a sleeve-like retainer, inwardly extending projections on said retainer defining seats for the reception of cutting nibs and a plurality of more than two nibs in said seats having mutually contacting faces, said nibs having side faces flaring outwardly in a direction from the cutting edges of the nibs toward the base thereof and having end surfaces inclined inwardly in said direction, said retainer having surfaces engaging said side faces and end surfaces to firmly retain said nibs.

6. A rock drill bit comprising a sleeve-like retainer, inwardly extending projections on said retainer defining seats for the reception of cutting nibs, a plurality of more than two nibs in said seats having mutually contacting faces, said nibs having side faces flaring outwardly in a direction from the cutting edges of the nibs toward the base thereof and having end surfaces inclined inwardly in said direction, said retainer having surfaces engaging said side faces and end surfaces to firmly retain said nibs, and a partition extending across said retainer in engagement with the bottoms of the nibs.

7. A rock drill bit comprising a sleeve-like retainer, inwardly extending projections on said retainer defining seats for the reception of cutting nibs, and a plurality of more than two nibs in said seats having mutually contacting faces, said nibs having side faces flaring outwardly in a direction from the cutting edges of the nibs toward the base thereof and having end surfaces inclined inwardly in said direction, said retainer having surfaces firmly pressed against said side faces and end surfaces to permanently retain said nibs.

8. A rock drill bit comprising a sleeve-like retainer, inwardly extending projections on said retainer defining seats for the reception of cutting nibs, a plurality of more than two nibs in said seats having mutually contacting faces, said nibs having side faces flaring outwardly in a direction from the cutting edges of the nibs toward the base thereof and having end surfaces inclined inwardly in said direction, said retainer having' surfaces engaging said side faces and end surfaces to firmly retain said nibs, and a partition extending across said retainer in engagement with the bottoms of the nibs, said retainer and partition being firmly pressed against said nibs to provide a permanent assembly.

9. In a device of the class described a non-cire cular drill rod, a retainer having a corresponding non-circular opening arranged to be applied to said drill rod, cutting nibs permanently secured in said retainer, said rod having a recess, said retainer having a hole therethrough in alinement with said recess when the retainer is applied to the rod, and a rivet element frictionally held within said hole with its inner end normally clear of said rod but adapted to be driven into saidrecess and flattened to unite the retainer with said rod.

10. In a device of the class described a polygonal drill rod, a retainer having a corresponding polygonal opening arranged to be apsquare opening arranged to be" applied to said drill rod, cutting nibs permanently secured in said retainer, said rod having a recess adjacent one of its corners, said retainer having a hole therethrough in alinement with said recess when the retainer is applied to the rod, and a rivet element frictionally held within said hole with its inner end normally clear of said rod but adapted to be driven into said recess and flattened to unite the retainer with said rod.

12. In a device of the class described a polygonal drill rod, a detachable bit comprising a retainer having a corresponding polygonal opening arranged to receive said rod, said rod having a pair of recesses in opposite corners thereof, said retainer having a hole therethrough in alinement with each of said recesses when the retainer and rod are assembled, and a rivet element frictionally held within each of said holes with its inner end normally clear of said rod but adapted to be driven into its 'alined recess and flattened to unite the retainer with said rod.

1 13. In a device of the class described a noncircular drill rod, a retainer having a corresponding non-circular opening arranged to be applied to said drill rod, cutting nibs permanently secured in said retainer, said rod having a recess, and means irictionally held by said retainer against accidental displacement but adapted to be driven into said recess to firmly unite the retainer with said rod, said means enabling said retainer to be applied freely to said rod prior to driving said means into said recess.

14. In a device of the class described a noncircular drill rod, a retainer having a corresponding non-circular opening arranged to be applied to said drill rod, cutting nibs permanently secured in said retainer, a partition formed of ductile material extending across said retainer in contact with said nibs, and means including a rivet element for uniting said retainer with said rod, said means permitting limited longitudinal movement of said rod within the'retainer to work said partition in the use of the device.

15. In a device of the class described a substantially polygonal drill rod, a bit including a retainer portion and cutting nibs, said retainer portion having a corresponding, substantially polygonal opening arranged to be applied to said drill rod, said rod having a recess adjacent one of its corners, said retainer portion having a hole therethrough in alignment with said recess when said retainer portion is applied to the rod, and a rivet element frictionally held within said hole with its inner end normally clear of said rod and adapted to be driven into said recess and flattened to unite the bit with said rod.

16. In a device of the class described a noncircular drill rod, a bit including a retainer portion and cutting nibs, said retainer portion hav ing a non-circular opening of form corresponding with that of the drill rod and arranged to be applied to said drill rod, said rod having a recess, said retainer portion having a hole therethrough in alignment with said recess when the retainer portion is applied to the rod, and a rivet element frictionally held within said hole with its inner end normally clear of said rod but adapted to be driven into said recess and flattened to unite the bit with said rod.

WILLIAM J. MCCALLUM. 

